Indirect gas-fired oven



Oct. 24, 1950 A. M. SAGE 2,527,200

INDIRECT GAS-FIRED OVEN Filed Oct. 5, 1945 5 Sheets-Sheet 1 IN V EN TOR.

A TTOENEY Oct. 24, 1950 5 Sheets-Sheet 2 Filed Oct. 5, 1945 Q Q 0 m 0 m o m m m QL Q Tm d J v k |1 l w m m m m w 0 o 4M 0 o w 0 m TI I 4 TTOQNEY Oct. 24, 1950 A. M. SAGE INDIRECT GAS-FIRED OVEN I 5, Sheets-Shae; :5

Filed Oct. 5, 1945 .."M@i .w WHUHHHw "m r A lllllllhl iL INVEN-TOR.

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Oct. 24, 1950 INDIRECT GAS-FIRED OVEN Filed Oct. 5, 1945 HVVENIORL mm H@ ,QTTCMWVEY Oct. 24, 1950 A. M. SAGE INDIRECT GAS-FIRED OVEN SI Sheet s-Sheet 5 Filed Oct. 5, 1945 iilllllill.

1 N V EN TOR. 14/502 M. 5/165 A TTOQ/VE Y The said heating unit 50 comprises a rectangular-shaped casing made up of the top wall bottom wall 52, side walls; 53 and 54, front wall 55 and rear wall 55. Each of the said Walls of the heater unit except the bottom wall 52, which is adjacently disposed to the-top wall M of the" oven, may comprise a pair of spaced steel plates with mineral wool insulation between the plates,

similar in purpose and function to the hereinbefore described construction of the walls of the oven. The bottom wall 52 of the heater unit 50 may be a steel plate and the entire unit 59 is mounted on the topwall' l4 of the oven by means of the angles 5'! and 58 which may be Welded to the side walls 53 and 54 and to the said top wall I4, in such manner as to provide a space 60 between the said bottom wall 52 and the top wall l4, as clearly shown in Figs. 2, 4, and 6 to 9 of the drawings.

The interior of the heater unit 59 is provided with an auxiliary wall 5| parallel to and spaced from the top wall 5| an auxiliary wall 52, parallel to and spaced from the side wall 54 and an auxiliary wall 63 parallel to and spaced from the rear wa1l56, the said auxiliary walls 6|, 62 and 63 serving to divide the heaterunit into two compartments 65 and 66, independently sealed off from each other, the compartment 65 serving as the combustion chamber and the compartment 66 serving as the air chamber. The air chamber 66 is provided with a blower compartment 68, housing a suitable blower device 16 of any standard type suitable for the purposes intended.

Disposed in the combustion chamber 65 and sealed off from direct communication therewith by the vertical walls H and 12 is an air duct I3 which communicates directly'with the duct 36 by means of an opening 14 in the bottom wall 52 of the heater unit 55 and an aligned opening 15 in the top wall H1 of the oven, as clearly noted in Figs.5and '7. I

As noted in Figs. 5 and 6 of the drawings, in that portion of the bottom wall 52 of the heater unit 50, constituting the air chamber 66, there is provided anopem'ng 59 communicating directly with the duct 3| in the oven l0, and which as noted in the drawings extends upwardly through an opening in the top wall l4 of the oven.

Mounted between the wall 12 of the duct 13 and the wall 63 of the combustion chamber 65 are a plurality of heat exchange pipes 86. lt'is noted that the pipes 96 are so arranged that they communicate directly with the duct 13 at one end and the blower Compartment'BB at the other end, the said pipes being disposed within the combustion chamber 65' and independently air 'sealed therefrom.

It is thus seen from the above described construction that when the blower I6 is in operation, air will be drawn by suction from the baking compartment 20 via the duct3| and the air chamber 66, into the blower through the opening 8| in the wall 82 of the blower compartment. It

will; then be forced through the pipes 80', into 4 the duct 73 and thence down into the duct 30 from where it will enter the baking compartment through the inlet ports 21, to provide a continuous circulatory air system passing through the baking compartment 20.

A suitable motor M supported on the wall 53 in any manner well known to the art, drives the blower shaft 16a throughthe pulleys 84 and 85 on the motor shaft and blower shaft 16 respectively and the interconnecting belt 86.

The following means are employed for heating the air in the above described circulatory system.

A burner or burners of any suitable design may be employed, such as for example, a pair of ribbon type pipe burners 88 passing through the front wall plate 55a and into the combustion chamber 65 extend horizontally substantially the entire length of said combustion chamber to which there is supplied gas from a source of supply, not shown. A mixer 89 of any well known standard type furnishes the proper mixture of air from the surrounding atmosphere with the gas before it enters the said burners 88. Asuit- 'able gas pilot burner 90 of the spark ignition type, well known to the art, is mounted on the plate 55a as shown in Fig. 6.

In accordance with my invention, I provide an exhaust fan 92 mounted in an exhaust duct 93, which in turn is mounted in the wall 53. An opening 94 in the casing communicates directly with the combustion chamber 65. When the exhaust fan 92 is operated the heated air in the combustion chamber 65, together with the products of combustion, are drawn out 'of the said chamber 65 and carried away through the duct 93. It is noted that the pipes 86 are disposed directly in the path of movement of these exhausted products of combustion so that-the said pipes 80 will'be heatedthereby. This will result in heating the air being recirculated through the said pipes 86. It is thus seen that the air supplied to the ducts 13 and 36 and passing horizontally across the baking compartment 2!] of the oven is heated to a predetermined degree, depending upon the needs of the articles undergoing processing. a

It is also seen from the above, that in accordance with my invention that I provides. separate and positive exhaust for alljthe products of combustion and that the suction of the exhaust fan creates a negative pressure in' the combustion chamber "which 'draws in sufficient primary air through the gas-air mixer of {the burners to support complete "combustion. "By such construction and arrangement the combustion chamber is completely sealed'oif from the surrounding air in the room, with the-result and by the interconnecting belt 91.

To provide a positivepressure'discharge of-a certain portion of the air" and fumes from the articles processed, there is provided an exhaust stack IOU-leading directly from the blower 1D and passing through-the 'wall 5| (see Fig. 4) to the atmosphere outside of the oven. The said exhaust stack I00 may be provided with a regulating'damper ll of the type having segments cutout to prevent full closing and to insure a safe minimum ventilation at all times, the balance of the discharge from the blower being forced through the tubes 80 to be recirculated as above described. Constant air flow and uniformity of temperature in all parts of the baking compartment may be obtained by adjustment of the inlet and outlet ports 27 and 28.

To compensate for the air exhausted through the stack I00 fresh air from the atmosphere surrounding the oven is admitted to the air chamber 60 through an inlet opening I in the bottom wall 52, to be subsequently drawn in to the blower to join the stream of recirculated air.

The inlet opening I05 communicates directly with the space 60 between the walls 52 and M, which in turn is open at the ends to the surrounding atmosphere, as shown in Fig. 4. It is notedthat the fresh make-up air is thus preheated by contact with the walls of the combustion chamber before it enters the recirculating stream.

Certain customarily employed electrically controlled safety measures may be employed so that the burners cannot be lighted unless the motor switch is on. Also certain similamwell known means may be employed so that the burners 88 U cannot be lighted unless the exhaust fan 92 is running. A suitable glass covered sight opening H0 may be provided in the front wall 55 of the heater unit.

The inlet and outlet ports 2? and 28 respectively, in the duct walls 25 and 26, are preferably constructed as shown in Figs. and 11 of the drawings. A less than 360 degree circular slit is made in the wall of the duct leaving a portion 21b uncut. The said duct wall 25 is preferably of bendable material and the portion 21a within the slit is manually bent away from the plane of said wall 25 to provide an opening 21 the size of which is determined by the amount which the said portion 27a is angularly bent. While in Figs. 10 and 11 I have illustrated the inlet ports 21, it is understood that the outlet ports 28 are similarly constructed.

In accordance with the provisions of the patent statutes, I have herein described the principle and operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means. Also, while it is deheat exchange pipes to heat the same.

signed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results outlined, and the invention extends to such use.

Having described my invention, I claim as new and desire to secure by Letters Patent:

1. In an indirect gas fired oven or the char acter described an independent heater unit having a combustion chamber, a gas burner in said combustion chamber and a gas-air mixer associated therewith, a baking compartment, an air inlet and an air outlet, said last named air inlet and outlet each communicating with said baking compartment and said heater unit, a plurality of heat exchange pipes directly in said combustioncha'mber and air sealed with respect thereto, and a recirculating blower, each of said heat exchange pipes communicating at one end with said blower and at the opposite end with said air outlet,

means for rendering said blower efiective to draw air from said baking compartment through said air inlet and to force the same through said heat exchange pipes to be heated thereby and thence through said air outlet into said baking compartment to pass therethrough to be again drawn out through said air inlet by said blower and recirculated, and means comprising an exhaust fan communicating directly with said combustion chamber to produce a negative pressure therein so that suficient primary air will be drawn in through the gas-air mixer and through the burner to support complete combustion.

2. An indirect gas fired oven according to claim 1 in which the said heat exchange pipes are arranged near one wall of said combustion chamber and in which said exhaust fan communicates directly with the interior of said combustion chamber through an opening in said last named wall so that the products of combustion exhausted by said exhaust fan will pass over said ALBERT M. SAGE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 321,336 Beard June 30,1885 1,045,915 Turner Dec. 3, 1912 1,536,427 Degner May 5, 1925 1,559,076 Collins Oct. 27, 1925 1,943,053 Boisset Jan. 9, 1934 2,040,328 Olson May 12, 1936 

